Step 1: Understanding the Question.
We are given a linear demand function for a light rail transit (LRTS) system, \(Q = 43000 - 850P\), where \(Q\) is the daily ridership and \(P\) is the fare per ride. We need the percentage rise in ridership when the fare drops from Rs. 30 to Rs. 25.
Step 2: Find the ridership at the original fare.
Put \(P = 30\) into the demand function:
\[ Q_1 = 43000 - 850(30) = 43000 - 25500 = 17500 \]
So at Rs. 30 per ride, 17,500 riders use the LRTS each day.
Step 3: Find the ridership at the reduced fare.
Put \(P = 25\) into the demand function:
\[ Q_2 = 43000 - 850(25) = 43000 - 21250 = 21750 \]
So at Rs. 25 per ride, ridership rises to 21,750 riders per day.
Step 4: Work out the percentage increase.
The rise in ridership is:
\[ \Delta Q = Q_2 - Q_1 = 21750 - 17500 = 4250 \]
The percentage increase, measured against the original ridership, is:
\[ \% increase = \frac{\Delta Q}{Q_1} \times 100 = \frac{4250}{17500} \times 100 = 24.2857\ldots\% \]
Final Answer:
Rounded off to two decimal places, the ridership increases by about 24.29%, which sits inside the accepted range of 24.00% to 25.00%.
\[ \boxed{24.29\%} \]